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The total length-otolith length (TL-OL), total length-otolith width (TL-OWi), total length-otolith weight (TL-OW) and total weight-otolith weight (TW-OW) relationships of seven fishes in the Marmara Sea, Turkey were calculated. Measurements of sagittal otoliths (length, width and weight) and individuals (total length and total weight) from these species (Gaidropsarus biscayensis, Mediterranean bigeye rockling; Arnoglossus kessleri, Scaldback; Solea solea, Common sole; Uranoscopus scaber, Stargazer; Lophius budegassa, Blackbellied angler, Lepidorhombus boscii, The four-spot megrim and Lesueurigobius friesii, Fries's goby) were given. Linear regression analysis (y = bx + a) was used to determine the relationship between each morphometric character and the coefficient of determination (r2) were calculated. Highest determination coefficient were determined for L. budegassa and A. kessleri to TW-OW, for S. solea, and U. scaber to TL-OL, for G. biscayensis and L. boscii to TL-OWi, for L. friesii to TL-OW. The relatively lower determination coefficients were found for G.biscayensis, compared with others. These relationships provide vital information on species identification and size estimation of fish in predator-prey studies, we believe these results will be useful in future studies of stomach contents., Marmara Denizi’nde ki 7 balık türünde balık boyu-otolit boyu (TL-OL), balık boyu-otolit genişliği (TL-OWi), balık boyu-otolit ağırlığı (TL-OW) ve balık ağırlığı-otolit ağırlığı (TW-OW) ilişkileri hesaplanmıştır. Bu türlere ait (Gaidropsarus biscayensis, Uzun Gelincik; Arnoglossus kessleri, Pisi Balığı; Solea solea, Dil Balığı; Uranoscopus scaber, Tiryaki; Lophius budegassa, Fener Balığı; Lepidorhombus boscii, Kancaağız Pisi ve Lesueurigobius friesii, Kaya Balığı) balık ölçümleri (boy ve ağırlık) ve otolit ölçümleri (boy, genişlik ve ağırlık) verilmiştir. Her bir morfolojik karakteristiğin arasındaki ilişkilerin tespitinde Doğrusal regresyon analizi (y = bx + a) kullanılmış ve determinasyon katsayısı (r2) hesaplanmıştır. En yüksek determinasyon katsayısı L. budegassa ve A. kessleri için TW-OW, S. solea, ve U. scaber için TL-OL, G. biscayensis ve L. boscii için TL-OWi, L. friesii için TL-OW ilişkilerinde hesaplanmıştır. Diğer türlerle karşılaştırıldığında, G. biscayensis için oldukça düşük determinasyon katsayıları bulunmuştur. Bu ilişkiler balıkların av-avcı ilişkileri çalışmalarında tür tayini ve av boyu tahmininde önemli bilgiler sunduğundan, gelecekte gerçekleştirilecek mide içeriği çalışmaları açısından katkı sağlayacağını düşünmekteyiz.

Fish fraud is a problematic issue for the industry. For it to be properly addressed will require the use of accurate, rapid, and cost-effective tools. In this work, near infrared reflectance spectroscopy (NIRS) was used to predict nutritional values (protein, lipids, and moisture) as well as to discriminate between sources (farmed vs. wild fish) and conditions (fresh or defrosted fish). Samples of five whitefish species—Alaskan pollock (Gadus chalcogrammu), Atlantic cod (G. morhua), European plaice (Pleuronectes platessa), common sole (Solea solea), and turbot (Psetta maxima)—including farmed, wild, fresh, and frozen ones, were scanned by a low-cost handheld near infrared reflectance spectrometer with a spectral range between 900 and 1700 nm. Several machine learning algorithms were explored for both regression and classification tasks, achieving precisions and coefficients of determination higher than 88% and 0.78, respectively. Principal component analysis (PCA) was used to cluster samples according to classes where good linear discriminations were denoted. Loadings from PCA revealed bands at 1150, 1200, and 1400 nm as the most discriminative spectral regions regarding classification of both source and condition, suggesting the absorbance of OH, CH, CH2, and CH3 groups as the most important ones. This study shows the use of NIRS and both linear and non-linear learners as a suitable strategy to address fish fraud and fish QC.

Populations along environmental gradients have the potential to adapt to their own local environments. It is important to understand these adaptations in fisheries stocks to fully inform fisheries management strategies. With this is mind, sea temperatures are an important cue in timing for many marine species, including sole in the North-East Atlantic Ocean. We used spawning data and modelled sea surface temperature (SST) data from sole subpopulations to examine the possibility of local adaptation of their spawning times to rising temperature. Climate window analysis was used, in a linear mixed model using mean spawning week and SST, to investigate statistically significant differences between subpopulations of sole. There was no evidence of local adaptation to changing temperatures for these subpopulations. This suggests that their spawning-time reaction to changing temperatures is currently due to their subpopulation’s mean plasticity. Using climate window analysis and modelled temperature data we have demonstrated a method of examining spawning changes in marine populations along a temperature gradient. Recruitment and spawning success are key elements of fisheries population models which contribute to fisheries management. Further understanding of the influence of temperature on recruitment will help inform future modelling.

Summary The metazoan parasites were investigated of two flatfish the common sole, Solea solea (n:140) and the scaldfish, Arnoglossus laterna (n: 22) in the Sinop coast of Black Sea from June 2015 to June 2017. A total of 15 metazoan parasite species belonging to Digenea (6), Cestoda (3), Acanthocephala (1), Nematoda (4) and Isopoda (1) taxonomic groups were identified. Solea solea was found to be infected by Condylocotyla pilodora, Proctoeces maculatus, Opecoelidae gen. sp., Metadena sp., Stephanostomum sp., Progrillotia sp., Capillaria gracilis, Cucullanus campanae, Solearhynchus rhytidotes and Nerocila orbignyi. Arnoglossus laterna was found to be infected by Lecithochirium musculus and Grillotia erinaceus. Scolex pleuronectis, Hysterothylacium aduncum and Dichelyne minutus were determined in both flatfish. Infection prevalence and mean intensity values were re- corded for each parasite species. Infection values for each parasite species in relation to season and fish size were also determined and compared as comparatively. This study is the first one assessing the metazoan parasites both of S. solea and A. laterna collected from the Turkish coast of Black Sea. While Condylocotyle pilodora and Capillaria gracilis are new parasite records for S. solea, Grillotia erinecaus is new parasite record for A. laterna. Moreover, this paper is the first report on occurrence of Opecoelidae gen. sp., Metadena and Stephanostomum genera in S. solea.

Connectivity between juvenile habitats and adult stocks is important for determining the resilience of local fisheries and the relative contribution of different juvenile habitat areas to adult populations. Otolith chemistry is commonly employed to differentiate between individuals from different juvenile habitat areas; whereby different environmental exposures, mediated by intrinsic physiological processes, produce different trace element concentrations in the biologically inert otolith. This study aims to determine if otolith chemistry can differentiate between juveniles of hybridising con-familials where they are found in the same habitat and to establish if otolith chemistry can effectively re-assign individuals to contiguous coastal juvenile habitat areas of the inner Danish waters (IDW). Sympatric pairs of juvenile European plaice (Pleuronectes platessa) and flounder (Platichthys flesus) caught together in a juvenile beam trawl survey, in areas where the two species hybridise, were used to address the first aim. Juvenile plaice and common sole (Solea solea) caught during the same survey were used to determine if otolith chemistry can correctly re-assign individuals back to contiguous coastal juvenile habitat areas. Laser ablation inductively coupled plasma mass spectroscopy (LA-ICPMS) was used to analyse the trace elements in edge spots of juvenile otoliths and Canonical Analysis of Principal Coordinates was employed to test the reassignment of individuals back to correct species or area. Using a suite of eight trace elements, ∼72% of individual plaice (∼70%) and flounder (∼73%) were correctly identified. Greater than two-thirds (∼67%) of plaice were correctly re-allocated to four juvenile habitat areas and close to four out of five (∼79%) individual sole were correctly re-allocated to three juvenile habitat areas. These results indicate that the hybridising con-familial plaice and flounder of the IDW warrant further attention and could be a valuable model system to assess how intrinsic and extrinsic factors influence elemental incorporation. Furthermore, this study shows otolith chemistry is a valuable tool for tracing marine fish back to juvenile habitat areas, even where they are found along contiguous coastal areas.

The existence of a temperature gradient across latitudes is crucial to explain the patterns presented in the early life-history characteristics of marine fish species over large geographical areas. Hence, the aim of the present work was to analyse the temperature-related pattern in the early life-history events and characteristics of the common sole, Solea solea, along most of its geographical distribution area, focusing on key nursery areas for this species: Venice lagoon (Italy), Mondego estuary (Portugal), Vilaine estuary (France) and Balgzand (Netherlands). Otolith microstructure from metamorphosed age 0 juveniles was used to estimate age, the pelagic larval and metamorphosis stages duration, and the spawning period. A latitudinal cline was found for the main processes of the early life cycle: spawning started in December in the southernmost areas (Mondego estuary and Venice Lagoon) and in February in the Balgzand population. Hatching started earlier in the Venice lagoon, where warmer water temperatures in the winter led to an earlier development. The longest pelagic stage was observed in the French coast populations, which differed significantly from those of the Mediterranean, while metamorphosis lasted longer in the North Sea (Balgzand), when compared with the Portuguese Atlantic coast (Mondego). Populations further north were characterized by higher growth rates, suggesting an adaptation to local conditions. Despite that several abiotic factors play an important role in flatfish early life history, the observed temperature gradient seems to be one of the most important drivers.

Information on stock status is available only for a few of the species forming the catch assemblage of rapido fishery of the North-central Adriatic Sea (Mediterranean Sea). Species that are caught almost exclusively by this gear, either as target (such as Pectinidae) or accessory catches (such as flatfishes apart from the common sole), remain unassessed mainly due to the lack of data and biological information. Based on cluster analysis, the catch assemblage of this fishery was identified and assessed using CMSY model. The results of this data-poor methodology showed that, among the species analyzed, no one is sustainably exploited. The single-species CMSY results were used as input to an extension of the same model, to test the effect of four different harvest control rule (HCR) scenarios on the entire catch assemblage, through 15-years forecasts. The analysis showed that the percentage of the stocks that will reach Bmsy at the end of the projections will depend on the HCR applied. Forecasts showed that a reduction of 20% of fishing effort may permit to most of the target and accessory species of the rapido trawl fishery in the Adriatic Sea to recover to Bmsy levels within 15 years, also providing a slight increase in the expected catches.

Marine organisms show population structure at a relatively fine spatial scale, even in open habitats. The tools commonly used to assess subtle patterns of connectivity have diverse levels of resolution and can complement each other to inform on population structure. We assessed and compared the discriminatory power of genetic markers and otolith shape to reveal the population structure on evolutionary and ecological time scales of the common sole (Solea solea), living in the Eastern English Channel (EEC) stock off France and the UK. First, we genotyped fish with Single Nucleotide Polymorphisms to assess population structure at an evolutionary scale. Then, we tested for spatial segregation of the subunits using otolith shape as an integrative tracer of life history. Finally, a supervised machine learning framework was applied to genotypes and otolith phenotypes to probabilistically assign adults to subunits and assess the discriminatory power of each approach. Low but significant genetic differentiation was found among subunits. Moreover, otolith shape appeared to vary spatially, suggesting spatial population structure at fine spatial scale. However, results of the supervised discriminant analyses failed to discriminate among subunits, especially for otolith shape. We suggest that the degree of population segregation may not be strong enough to allow for robust fish assignments. Finally, this study revealed a weak yet existing metapopulation structure of common sole at the fine spatial scale of the EEC based on genotypes and otolith shape, with one subunit being more isolated. Our study argues for the use of complementary tracers to investigate marine population structure. ispartof: PLOS ONE vol:15 issue:11 ispartof: location:United States status: published

International audience; Coastal and estuarine nurseries are composed of habitats with different biotic and abiotic features. Quantifying the contribution of different habitats within nurseries to juvenile fish feeding would help identify those that are essential in the completion of their life cycle, by providing food resources that maximise growth and survival. Essential habitats for four bentho-demersal fish species (whiting, sea bass, plaice and common sole) in an estuarine nursery were identified using gut contents and stable isotopes. Habitats differed in isotopic ratios and benthic communities. The estuarine gradient defined the macrofauna communities and sources of organic matter used by primary consumers. Trophic niche overlaps and trophic contribution of habitats highlighted that the species used both intertidal and subtidal habitats as feeding grounds. Flatfish were local feeders and fed on prey available mainly in the habitat in which they were caught, suggesting feeding behaviour that required little energy for movement. Sea bass were concentrated in upstream habitats, with intertidal mudflats contributing for nearly half of its diet. Whiting had an ubiquitous feeding strategy, suggesting that it may target prey with the most energetic gain in the habitats. Hence, habitats were used simultaneously during the same season or asynchronously throughout the year by the juvenile fish studied, suggesting no preference for a specific habitat at the community scale. Finally, both trophic tracers demonstrated the trophic importance of intertidal mudflats, especially for the sea bass and common sole, with contributions up to the half and two-third of their diet respectively.

The amount of potentially toxic chemicals in a fish depends on various environmental factors, such as temperature and feeding ecology, which can be affected by Global Changes (GC). The main objective of the present work was to study the relative influence of temperature, food quality and food availability on the growth and contamination of juveniles of common sole (Solea solea), a marine flatfish species known to be a relevant indicator of the nursery quality. It focuses on two Persistent Organic Pollutants (CB153 and L -PFOS) of legacy and emerging concern, respectively. To achieve this, we used a toxicokinetic (TK) model in which toxicant flows are mechanistically predicted using a bioenergetic model based on the Dynamic Energy Budget (DEB) theory. This modelling framework was applied to juvenile sole from the Gironde estuary (SW France) and allows accounting for the influence of environmental conditions on fish biological processes involved in toxicant fluxes. To compare their respective influence on model predictions of age, length, and contamination at puberty, we included in a global sensitivity analysis: (1) environmental variability gathered from literature for this particular estuary and (2) TK parameters (i.e. assimilation efficiency AE and elimination rate k ˙ e ) variability and uncertainty gathered from literature about each contaminant but for different fish species and experimental conditions. Then, model predictions were confronted to fish contamination measurements from the Gironde Estuary with different combinations of TK parameter values from literature. Results highlighted a key role of diet composition on fish contamination and growth while water temperature only affected growth. It stressed the need to focus on GC impact on benthic communities and their consequences on juvenile fish diet for future work on GC scenarios. Furthermore, for both chemical, the range of variability of TK parameters from experiments led to underestimated fish contaminations. The best model fits were obtained using TK parameter values from model applications: from Mounier et al. (n.d.) for CB153 (Solea solea, experiment, AE=0.8 and k ˙ e =0 d−1) and from de Vos et al. (2008) for PFOS (food chain of the Western Scheldt estuary, The Netherlands, AE=0.8 and k ˙ e =0.8 10−2.d−1).

In the present study, the histological-based condition of common sole (Solea solea) larvae in the English Channel was evaluated to assess the relevance of experimentally-calibrated indices for wild collected specimens. Based on topographical observation of foregut, midgut, hindgut, liver and pancreas, each of the 202 larvae analysed was attributed one of the six grades of a condition index that was developed for sole in the nineties. In parallel, a synthetic table of 20 criteria historically used as condition indicators was created from an extensive review of the literature. These criteria were related to tissular integrity, cells height, nuclei, presence of prey and vacuolisation of the same five target organs. For each larva, each criterion was scored on a scale from one to three. Multiple correspondence analyses coupled to clustering and indicator values were used to explore the relationship between the condition index and criteria as well as to highlight which complementary information the latter could provide to the former. Results showed that some adjacent grades were related to the same set of scored criteria, suggesting that these grades are not as distinguishable in the field as they can be in controlled conditions. Some criteria like vacuoles in the enterocytes, size of the hepatocytes, amount of zymogen, stain of acini, presence of prey in the digestive tract and goblet cells in the foregut, were independent of the condition index and depicted more recent food intake than a true condition status. Conversely, criteria related to tissular integrity as well as presence of energetics reserves like vacuoles in the liver appeared more relevant to evaluate the condition status of fish larvae since their increasing scores were associated to different grades. It is concluded that the grading system obtained from experimental observations may not be adapted to reflect the different larval condition states that could be encountered in the field. A simplified grading system, based on three grades and a reduced set of relevant criteria is then proposed.

Fishery discard survival depends on multiple conditions; caution is essential when survival study outputs are employed to support management decisions. The study presents a stepwise procedure, devised to estimate discard survival, that accounts for the variability characterizing commercial fishing practices. The procedure was applied to the first survival study performed onboard rapido trawlers targeting Solea solea in the Mediterranean Sea. Undersized specimens collected during sorting were assessed for vitality; some were retained for captive observation. The main drivers affecting discard survival at the time of catch sorting (immediate survival) were identified and used to outline four different operational conditions set (scenarios). Immediate survival in each scenario was subsequently modified by applying a hazard coefficient of survival after 5 days of captive observation in relation to each vitality class, thus obtaining relative survival estimates following discarding. Temperature and air exposure duration were found to exert a major effect on survival, with catch weight and seabed type being additional important factors. The relative survival rate showed an aggregate value of 22.9% (10.5–33.4%). Scenario approach can enhance our understanding of the stressors influencing discard survival. The outcomes are discussed to explore the potential applications of the procedure to the identification of mitigation strategies.

This study extends our knowledge of the bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) in marine organisms and investigates its possible determinants. PAH levels were measured in Solea solea tissue and in marine sediments collected from three areas of the northern Adriatic Sea characterized by different anthropic impacts (Venetian Lagoon, Po Delta, and fishing grounds off Chioggia). The possibility of differential PAH bioaccumulation in different tissues (muscle, liver and gills) was investigated by seeking relationships between mean individual and total PAH concentrations in tissue and sediment samples, the physicochemical properties of PAHs (rings and Kow), and some key biological variables (lipid content of tissues, body size, habitat). The present study demonstrated that the lipid content might not be the only determinant of PAH bioaccumulation in common sole tissues. The habitat characteristics, the tissue types and some physicochemical properties of compounds were closely related to PAH bioaccumulation.

Summary This study determined prey consumption in common sole as a function of prey size (0–0.5, 1–1.5, 2–2.5 and 4–5 g), sediment thickness (20 cm and 2 cm) and fish size (50 g, 125 g or 300 g). Prey consumption (in numbers of prey eaten per fish per day) was reduced with increasing prey size and sediment thickness, and was increased with increasing fish size (p

Climate change not only alters ocean physics and chemistry but also affects the biota. Larval dispersal patterns from spawning to nursery grounds and larval survival are driven by hydrodynamic processes and shaped by (a)biotic environmental factors. Therefore, it is important to understand the impacts of increased temperature rise and changes in wind speed and direction on larval drift and survival. We apply a particle-tracking model coupled to a 3D-hydrodynamic model of the English Channel and the North Sea to study the dispersal dynamics of the exploited flatfish (common) sole (Solea solea). We first assess model robustness and interannual variability of larval transport over the period 1995-2011. Then, using a subset of representative years (2003-2011), we investigate the impact of climate change on larval dispersal, connectivity patterns and recruitment at the nursery grounds. The impacts of five scenarios inspired by the 2040 projections of the Intergovernmental Panel on Climate Change are discussed and compared with interannual variability. The results suggest that 33% of the year-to-year recruitment variability is explained at a regional scale and that a 9-year period is sufficient to capture interannual variability in dispersal dynamics. In the scenario involving a temperature increase, early spawning and a wind change, the model predicts that (i) dispersal distance (+70%) and pelagic larval duration (+22%) will increase in response to the reduced temperature (–9%) experienced by early hatched larvae, (ii) larval recruitment at the nursery grounds will increase in some areas (36%) and decrease in others (-58%), and (iii) connectivity will show contrasting changes between areas. At the regional scale, our model predicts considerable changes in larval recruitment (+9%) and connectivity (retention -4% and seeding +37%) due to global change. All of these factors affect the distribution and productivity of sole and therefore the functioning of the demersal ecosystem and fisheries management. This article is protected by copyright. All rights reserved.

In this study, concentrations of heavy metals were determined by ICP-MS in the edible tissues of common sole (Solea solea Linnaeus, 1758), whiting (Merlangius merlangus Linnaeus, 1758), silver sillago (Sillago sihama Forsskal, 1775) and muscle-exoskeleton of green tiger shrimp (Penaeus semisulcatus De Haan, 1844), from the seas of Iskenderun Bay, Eastern Mediterranean, Turkey, in January–February, 2016. The lowest and highest mean concentrations of Mn, Cr, Cd, Ni, Hg, As, Pb, and Co in fish and shrimp’ muscles were found, respectively, as follows: 0.166–0.382, 0.134–0.336, 0.005–0.008, 0.091–0.140, 0.026–0.228, 1.741–29.254, 0.087–0.110, and

Connectivity between spawning and nursery grounds influences the colonization, replenishment and resilience of populations of marine organisms. Connectivity rate, measured as the exchange of individuals between spawning and nursery grounds, is therefore a crucial determinant of stock size. However, connectivity of early-life stages is hard to explore due to sampling limitations and insufficient knowledge on potential larval sources. Here we present new insights into pre- and post-settlement dispersal of the common sole (Solea solea L.) at a spatial scale of 5–500 km in the Southern North Sea. Patterns at a scale of

© 2018, Springer Nature Switzerland AG. While otolith shape analysis can provide a valuable tool for discriminating between fish populations, factors which may influence otolith shape, such as the effect of size, directional asymmetry in growth, and local environmental conditions, are often unknown. Here, we analyzed differences in otolith shape across three size classes of age-0 common sole Solea solea L. from nursery grounds off the Belgian coast and in the Wadden Sea. Across size classes, form-factor decreased and roundness remained consistently high in both nursery grounds, while ellipticity increased in the Belgian nursery. Directional asymmetry between left and right otoliths measured by Fourier coefficients accounted for 0.96 and 7.2% of the variance when comparing otoliths overall, and for each size class, respectively. Within the Belgian nursery, results were consistent across sampling years and locations. In addition, otolith shape was marginally different between nursery grounds, but highly variable within nursery grounds. A small divergent group, which seems partly related to fish size, was noted at both spatial and temporal scales. Based on these results and before embarking on a study of population structure using otolith shape in age-0 common sole, we recommend testing for directional asymmetry and fish size effects across the entire region of interest. ispartof: HYDROBIOLOGIA vol:845 issue:1 pages:95-108 status: published

The management of coastal fisheries and coastal marine areas both require information on the use and importance of coastal marine habitats for marine species. This information is certainly pertinent for exploited species dependent on these coastal habitats for specific life-history stages. This study uses two different measures of habitat suitability to build Habitat Association Models (HAMs) and Habitat Growth Models (HGMs) for juveniles of three commercially and recreationally important fish species (Pleuronectes platessa, Platichthys flesus, and Solea solea) of the Inner Danish Waters (IDW). A large scale, one-off juvenile survey was used to collect juvenile fish and directly observed environmental data. The survey informed Generalised Linear (Mixed) Models (GLMs and GLMMs), which were fit and run through repeated random sub-sampling cross-validation before being utilised to build interpolative maps of both prediction and model uncertainty. The limitations of this approach are discussed in reference to the future works required to complement and improve such static habitat suitability maps. These results can be used to inform marine spatial planning and future work into the role of juvenile habitats in supporting fishery species.

Common sole (Solea solea) aquaculture production is based mostly on wild-caught breeders. Recently, the successful reproduction of first-generation fish that were reared in captivity was accomplished. A consistent good quality and quantity of produced eggs throughout the year, and of next-generation broodstock, is important for reducing the overall cost of production.Hoxgenes play a pivotal role in normal embryonic development and alterations of their temporal expression level may be important for egg viability. Expression profile analysis of fivehoxgenes (hoxa1a,hoxa2a,hoxa2b,hoxb1aandhoxb1b) involved in early embryonic development and ofhoxa13a, which is involved in late stages, was carried out. Results revealed a premature and/or maternal expression ofhoxa13ain sole embryos, and the detection ofhoxa2aandhoxa2bgenes as members of paralog group 2. Principal Component Analysis ofhoxgene expression in 54 ± 6 hours post fertilization embryos coming from wild-caught broodstock and a first-generation one reared in the hatchery, unveiled that these broodstocks are clearly distinct. In addition, their pairwise comparison revealed significant differences in the expression levels ofhoxb1aandhoxb1bgenes.Hoxgene regulation during embryonic development could give valuable insight into rearing sole broodstocks with different origin in concert, and also into gaining a steady mass production of eggs, either in quality or quantity, all year round.

A.L. Primo and F. Martinho are funded by national funds (OE), through FCT (Portuguese Foundation for Science and Technology), I.P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19. A. Vaz is funded by the FCT (Portuguese Foundation for Science) through a PhD grant (SFRH/BD/137862/2018). Financial support was obtained through the project “Mytag - Integrating natural and artificial tags to reconstruct fish migrations and ontogenetic niche shifts” (PTDC/MAR-EST/2098/2014), under the Project 9471 – Reforçar a Investigaçao, ˜ o Desenvolvimento Tecnologico ´ e a Inovaç˜ ao (Projeto 9471-RIDTI) and subsidized by the European Regional Development Fund (FEDER, POCI-01-0145-FEDER-016787) and through the strategic plan of the Centre for Functional Ecology - Science for People and the Planet (CFE) (UIDB/04004/2020), financed by FCT/MCTES through national funds (PIDDAC). Additional support was also obtained via project “RENATURE - Valorization of the Natural Endogenous Resources of the Centro Region” (CENTRO-01-0145-FEDER-000007), funded by the Comissão de Coordenacã̧o da Região Centro (CCDR-C) and subsidized by the European Regional Development Fund (FEDER). We also acknowledge the support from the Integrated Program of SR&TD “SmartBioR” (reference Centro-01-0145-FEDER-000018, cofunded by CENTRO2020/PORTUGAL2020/FEDER). Understanding the causes of variation in recruitment of marine fishes has been a central goal over the last century. However, the relationship between year class strength and larval growth and survival is poorly known for most species. The main goal of this study was to investigate the relationships between larval traits and year class strength of two flatfish species in an nursery estuary. We examined the effects of the variation in the early life characteristics (pelagic larval growth, pelagic larval duration, size-at-hatching and size-at-settlement) on post-settlement survival of flounder Platichthys flesus and common sole Solea solea in the Mondego estuary (Portugal) over a 5-year period (2011–2015). The two flatfish species showed distinct larval traits variation during the study period, mainly related with location of the spawning ground and intrinsic biologic patterns. Flounder was able to delay metamorphosis while gathering energy and/or waiting for suitable environmental cues from estuarine origins while sole take advantage of better environmental conditions due to a later hatching. Early fast growth were strongly related with subsequent growth, affecting larval survival. Both growth and larval traits variation during the studied period were strongly related with temperature. This study highlights the importance of early growth for fish survival and contributes with key information on fish early life stages that will support a better management of fish stocks. info:eu-repo/semantics/publishedVersion

In the eastern part of the English Channel, common sole (Solea solea) has strong interests in fisheries research. Low recruitment along with a decline in spawning stock biomass have been observed for several years. According to the recruitment hypotheses, larval survival may play an important role that needs to be considered. The fish larval condition can be assessed using histology which has been recognised as the most appropriate method to provide a reliable index of the nutritional status. Based on this approach, this study aimed to identify critical periods of wild-collected sole larvae and to determine sources of variations of their condition between two periods separated by more than 20 years. In line with other studies, the transition from endogenous to exogenous feeding was identified as the most critical period with the lowest proportion of healthy larvae observed. During this first feeding stage, good larval conditions were located in sampling stations close to the coast and at the end of the spring season, in relation to higher temperature and fluorescence values. This highlights the need for sole larvae survival to cross the coastal front, which splits the central and coastal waters, to reach more stable and productive areas. This coastal migration pattern was consistent between 1995 and 2017, with however significantly lower larval abundances in the recent period. Multivariate analyses showed that the spring environmental conditions of 1995, characterised with lower temperature and higher fluorescence values were more favourable to larval condition, compared to the spring in 2017. Areas providing suitable environmental conditions in 2017 were more restricted and limited to sampling stations in front of estuaries. Since small differences in larval survival can lead to large fluctuations in recruitment, the larval condition should be studied in a more long-term approach. This would provide a better understanding of the environmental influence on larval survival and recruitment success.

International audience; The sustainable exploitation of sea resources is based on the understanding of population distribution, structure and functioning. The mismatch between stock units and fish populations can dramatically bias the assessment and lead to irrelevant or even detrimental management measures. The common sole of the Eastern English Channel (EEC; ICES division VIId) is a flatfish species of high interest that has been overexploited over the last decades. Low connectivity induced by early life stages across the stock was previously known, but gaps remained regarding the role of adults in population connectivity and spatial structure. In this study we have filled these gaps by (1) gathering all the information on stock identity through five population- and individual-based approaches, and (2) combining this information in a semi-quantitative framework, i.e. the Stock Differentiation Index (SDI). Regarding the population-based approaches, growth and abundance-at-age analyses highlighted a lasting signal of population structure, with three population subunits. Regarding the individual-based approaches, genetic analysis highlighted low but significant genetic differentiation between the three subunits over an evolutionary time scale. Besides, a mark-recapture study demonstrated a low level of exchange between these subunits. Finally, an analysis of otolith shape pinpointed spatial variation between the three subunits. Overall, the SDI = 0.93 suggested evidence of spatial structure. The misalignment of the current stock definition with the underlying biological metapopulation now requires the improvement of the assessment-management to ensure its sustainable exploitation.

Bu calisma, Turkiye’nin onemli av sahalarindan birisi olan Gulluk Korfezi’nde kullanilan dil fanyali uzatma aglarinin secicilik parametrelerinin tespit edilmesini amaclamistir. Orneklemeler, ag goz boyu 80 ve 90 mm olan fanyali dil aglari ile Kasim 2013 - Aralik 2015 tarihleri arasinda gerceklestirilmistir. Calisma suresince toplam 1209 adet birey yakalanmistir. Secicilik parametrelerinin belirlenmesinde SELECT yontemi kullanilmistir. Kullanilan fanyali ag verileri icin en iyi uyumu bi-modal model vermistir. Bi-modal modele gore optimum yakalama boylari 80 ve 90 mm’lik aglar icin sirasi ile 23,20 ve 27,02 cm olarak bulunmustur. Ayrica 80 ve 90 mm ag goz boyuna sahip dil uzatma aglarina ait ilk yakalama boylari (Lc) sirasi ile 20,37 ve 24,11 cm ve birim cabadaki av miktari (CPUE) 2,94 ve 1,43 kg/1000m olarak hesaplanmistir. CPUE degerlerinden de anlasilacagi gibi av baskisi buyuk boylu bireyleri etkilemektedir. Bu durum, ureyen stok biyokutlesinin her yil azalmasi ve ayrica dogal ve balikciliktan kaynaklanan olumler de dusunuldugunde neslin devamini saglayacak kucuk boylu bireylerin gelecek donemlerde cok az sayida olacagi anlamina gelmektedir. Ticari avciligi duzenleyen tebligde dil baligi icin asgari boy siniri 20 cm’dir. Ilk yakalama boyunun bu sinira cok yakin olmasi nedeni ile ag goz boylarinin duzenlenmesine ihtiyac duyulmamistir. Ancak kullanilan ag posta sayilarinda ciddi duzenlemeler yapilmalidir.

International audience; Studying adverse effects of chemical pressure on aquatic ecosystems needs a comprehensive knowledge of bioaccumulation mechanisms of pollutants in biota to predict internal concentrations, especially for Persistent Organic Pollutants (POPs). However, the large variability of responses in measured POP concentrations requires explicit consideration of both individual variability and environmental influences. Dynamic Energy Budget (DEB) theory provides a rigorous and generic conceptual framework for tackling these questions in a relevant mechanistic way. In the present study, parameterisation and calibration of previous DEB models for Solea solea were revisited in order to accurately represent the full life cycle with an original emphasis on larval stage, metamorphosis, reproduction rules and sexual differences. We first improved calibration thanks to the use of the estimation procedure developed by the DEB network coupled with a broad compilation of data from literature. Then, we validated this set of parameter estimates on independent datasets of i) individual monitoring of larval growth in controlled food conditions from a novel experiment, and ii) juvenile and adult growth, and female fecundity, from a natural population. Finally, we combined the DEB model developed in the present paper with we used a simple toxicokinetic (TK) model from literature. This TK model was also combined to a previous DEB model and was used to reproduce the mean trajectories of a growth and contamination dataset. We applied the same TK model with our DEB model considering inter-individual variability in food availability. This application highlighted the need to accurately consider inter-individual variability in ingestion to correctly estimate growth and contamination variability. The present work is the first step in the development of a mechanistic TK model that will be used in a companion paper for investigations of juvenile sole sensitivity to warming, nursery quality and prey contamination, in highly fluctuating estuarine environments.

Modifying the design and selectivity of commercial fishing gears can reduce unwanted catches. Most gear selectivity research focusses on trawl gears, and there are relatively few examples of modified static nets, such as gill and trammel nets, which are used all over the world. Fishers operating in the southeast England’s common sole (Solea solea) static net fishery wanted to explore methods to try to reduce the unwanted catches of thornback ray (Raja clavata). In 2017, the fishery had common sole landings of 343 tonnes making it an important local fishery. The largest port, the beach launch port of Hastings, is the home port for 65 vessels. Here we describe the performance of a modified trammel net with reduced mesh size in the two outer walls, intended to reduce catches of thornback rays without reducing the landings of the target species of common sole. There no published studies on modifying the outer meshes of a trammel net. The fieldwork was undertaken onboard a vessel from Hastings, fishing over ten days. The catches from a standard gill net, a standard trammel net and a modified trammel net were compared. Six fleets of nets were fished, each made up of five different net sections. The three net designs were placed into the fleets in a random set design. All of the net designs had a minimum (inner) mesh size of 90 mm. There was no statistically significant difference in the number of thornback ray caught between the nets but the number of common sole was estimated at 87 % higher by value in the modified trammel net compared to the other nets. Therefore, when using the modified trammel net, considerably less fishing effort was required to catch the same quota of common sole, but with no increase in the rate of thornback ray catches. If this design were to be applied more widely in this fishery, it could reduce overall catches of thornback ray. The study shows the difference in selectivity towards common sole, plaice (Pleuronectes platessa), whiting (Merlangius merlangus) and thornback rays between a gill net and two trammel net designs.

This study aims to describe the selectivity features of European hake gillnet for Merluccius merluccius (European hake, target species) and Solea solea (common sole, by-catch species) in the southern Sea of Marmara in terms of small-scale fisheries. For this purpose, the size selectivity of gillnets for European hake and the common sole was studied in the Sea of Marmara. Experimental fishing operations were carried out by using gillnets with a mesh size of 28, 30 and 32 mm. A total of 523 specimens of European hake and 418 specimens of common sole were caught. Total lengths ranging from 23.5 to 41 cm were recorded for European hake and from 18.5 to 35.5 cm for the common sole. The experimental data estimated by applying the SELECT method showed that the bi-modal and log normal models gave the best fit for European hake and the common sole selectivity, respectively. Estimated modal lengths were found to be 30.61; 32.80; 34.99 cm for European hake and 19.94; 21.37; 22.79 cm for common sole for each mesh size studied. The present study is the first report on the selectivity of these species using the SELECT method for European hake gillnets in Turkey. The results obtained from the present study show 30 mm mesh size which is used currently by fishermen is highly selective and very suitable for sustainable fisheries both European hake and common sole. These findings will help to improve the management and conservation of small-scale fishery, especially, in this region.

International audience; An accurate representation of the spatial structure of marine fish populations is a prerequisite for unbiased stock assessment, to build appropriate management measures. The common sole (Solea solea, L.) of the Eastern English Channel (EEC) is a commercial flatfish species, whose stock is currently assessed as a single homogeneous population and has been overexploited over the last decade. Previous studies have highlighted the stock's low connectivity and the lack of understanding in sub-adults and adults mixing between putative subunits, raising the issue of a potential spatial structure of this stock. Here, we examined evidence of spatial structure by analyzing spatiotemporal patterns of length and density-at-age using time series (1989–2015) obtained from a scientific survey (UK-BTS). We tested for various hypotheses of spatial structure, based on both scientific and expert knowledge, including three isolated subunits, their combination, and no spatial structure. We combined two sets of analyses: (1) a selection of the von Bertalanffy growth model with spatial effects capturing the most accurate spatial structure of the stock and the analysis of long-term spatial patterns (gradients, trends, synchrony) in growth parameters; and (2) an analysis of the synchrony among density-at-age time series between spatial subunits. Growth analysis revealed a spatial structure in three subunits (i.e. the southwestern, northeastern and English parts of the EEC) and an overall decline of length-at-age, suggesting Fishery-Induced Evolution. The synchrony analysis revealed high spatiotemporal integrity at the level of the southwestern subunit of the EEC. Our two analyses thus detected a lasting signal of spatial stock structure with a probable isolation of the southwestern subunit from the rest of the EEC. Future research should build on our study by investigating the connectivity of sole throughout its entire life cycle, to improve stock assessment and fishery management.; Une représentation exacte de la structure spatiale des populations de poissons de mer est une condition préalable à une évaluation impartiale des stocks, afin d'élaborer des mesures de gestion appropriées. La sole commune (Solea solea, L.) de la Manche orientale (CEE) est une espèce commerciale de poisson plat, dont le stock est actuellement évalué comme une seule population homogène et a été surexploité au cours de la dernière décennie. Des études antérieures ont mis en évidence la faible connectivité du stock et le manque de compréhension chez les sous-adultes et les adultes se mélangeant entre sous-unités putatives, ce qui soulève la question d'une structure spatiale potentielle de ce stock. Nous avons examiné ici les preuves de la structure spatiale en analysant les tendances spatio-temporelles de la longueur et de la densité selon l'âge à l'aide de séries chronologiques (1989-2015) obtenues à partir d'une enquête scientifique (UK-BTS). Nous avons vérifié diverses hypothèses de structure spatiale, fondées sur des connaissances scientifiques et spécialisées, y compris trois sous-unités isolées, leur combinaison et l'absence de structure spatiale. Nous avons combiné deux ensembles d'analyses : (1) une sélection du modèle de croissance de von Bertalanffy avec des effets spatiaux capturant la structure spatiale la plus précise du stock et l'analyse des modèles spatiaux à long terme (gradients, tendances, synchronie) des paramètres de croissance ; et (2) une analyse de la synchronisation entre les séries temporelles de densité à âge entre sous-unités spatiales. L'analyse de la croissance a révélé une structure spatiale dans trois sous-unités (c'est-à-dire les parties sud-ouest, nord-est et anglaise de la CEE) et un déclin global de la longueur selon l'âge, ce qui suggère une évolution induite par la pêche. L'analyse synchrone a révélé une grande intégrité spatio-temporelle au niveau de la sous-unité sud-ouest de la CEE. Nos deux analyses ont ainsi détecté un signal durable de la structure spatiale du stock avec un isolement probable de la sous-unité sud-ouest du reste de la CEE. Les recherches futures devraient s'appuyer sur notre étude en étudiant la connectivité de la sole tout au long de son cycle de vie, afin d'améliorer l'évaluation des stocks et la gestion des pêches.

Identifying nursery habitats is of paramount importance to define proper management and conservation strategies for flatfish species. Flatfish nursery studies usually report upon habitat occupation, but few attempted to quantify the importance of those habitats to larvae development. The reliance of two sympatric flatfish species larvae, the European flounder Platichthys flesus and the common sole Solea solea, on the estuarine food web (benthic versus pelagic), was determined through carbon and nitrogen stable isotope analysis. The organic matter sources supporting the production of P.flesus and S.solea larvae biomass originates chiefly in the benthic food web. However, these species have significantly different C-13 and N-15 values which suggest that they prey on organisms that use a different mixture of sources or assimilate different components from similar OM pools (or both). MIGRANET Programa Operativo de Cooperacion Territorial del Espacio Sudoeste Europeo-SUDOE national funds by Fundacao para a Ciencia e a Tecnologia (FCT, Portugal) [UID/Multi/04423/2013] European Regional Development Fund (ERDF) [PT 2020] FCT [SFRH/BPD/104019/2014, SFRH/BPD/40832/2007, INCENTIVO/ MAR/UI0350/2014]

Micronuclei (MN) and nuclear buds (NB) frequency was assessed monthly over a one-year period in erythrocytes of common soles (Solea solea) from the Basque continental shelf, a minor disturbed area, in order to determine baseline levels and potential biotic and abiotic confounding factors within biomonitoring purposes. Both genotoxic parameters presented seasonal variations, although only NB frequency was positively correlated with environmental variables (i.e. water temperature and salinity). On the contrary, MN and NB were not affected by age and gender. Therefore, samples of combined age and gender can be used for biomonitoring genotoxic effects, although sampling period together with water temperature and salinity should be thoroughly considered for NB. Overall, these findings are the first attempt to establish baseline MN (0.10-0.78‰) and NB (0.13-0.82‰) frequencies in common sole from Basque marine waters, which are useful for upcoming data comparisons and integration within genotoxicity evaluation procedures of similar marine environments under biomonitoring scopes.

We examined the influence of prey density and fish size on prey consumption in common sole (Solea solea L.) foraging on buried ragworm Alitta virens (Sars) (formerly known as Nereis virens (Sars)). The tested prey densities of 0.8, 2.2, 4.3 and 6.5 individuals dm−2 were exposed to common soles of either 100 g or 300 g. At each prey density common sole foraged for 48 h. At both common sole classes studied, a positive correlation between prey consumption and prey density was observed (P P P = 0.018). Small common sole reached satiety prey consumption rates at nearly every prey density while large common sole did not reach satiation rates even at highest prey densities. The data suggest that in nature, polychaetes such as A. virens may contribute to the diet of small common sole even when they are only moderately abundant. In contrast, polychaetes may not be an ideal prey for larger common sole as indicated by the absence of satiety regardless of prey density.

research program SMAC (France Filiere Peche); research program SMAC (DPMA); research program SMAC (IFREMER); research program SMAC (Agrocampus Ouest); research program SMAC (region Hauts-de-France); research program SMAC (region Normandie)l; In fisheries science, a mismatch between the delineation of a fish stock and the underlying biological population can lead to inaccurate assessment and management. Previous results suggested a potential spatial structuration of the Eastern English Channel (EEC) stock of common sole, Solea solea, in three sub-populations. In this article, we propose to investigate the spatial population structure of common sole in the EEC using the von Bertalanffy Growth Function parameters as indicators of population segregation. In order to test the sub-population hypothesis and evaluate its robustness to data sources, we developed three models, all including an area effect on growth parameters. The first model was aimed at testing a potential data source effect (in addition to the area effect) using commercial and scientific survey data jointly. The two other models used either scientific survey or commercial fishery data and focused on spatial differences in growth parameters. Our results showed that the growth parameter estimates indeed differed depending on the type of data used, with higher estimated asymptotic length and length at age two (L-2) using commercial data. They also highlighted spatial differences in asymptotic length, consistent between models, which tend to confirm a spatial structuration of sole in the EEC. While these results need to be strengthened by marking and genetic studies, they constitute a first step towards a better understanding of the population spatial structuration of common sole in the EEC.

none 14 si In the Adriatic Sea two cryptic species of sole coexist, the common and Egyptian sole. Soles are one of the most valuable demersal fishery resources in the Adriatic Sea, so a correct species identification is crucial in order to perform stock assessment and implement effective management measures based on reliable and accurate data. In this study specimens collected during fishery independent and fishery-dependent activities in the Adriatic were analysed and identified coupling morphological and genetic approaches. A comparison of these two methods for the sole species identification was carried out to assess the most effective, accurate and practical diagnostic morphological key-character(s). Results showed that external characters, in particular features of the posterior dorsal and anal fins, are valid and accurate morphological markers. Based on these traits, a practical identification key of the two sibling species was proposed. Moreover, it was possible to estimate the extent of the error due to species misidentification introduced in the common sole stock assessment carried out in the Northern-central Adriatic Sea (GSA17). A 5% bias in the correct identification of common sole specimens was detected. However, this bias was shown not to affect the common sole stock assessment. Moreover, the genetic profiling of the Adriatic common sole allowed estimating genetic diversity and assessing population structure. Significant divergence between common soles inhabiting the eastern part of the Southern Adriatic Sea and those collected from the other areas of the basin was confirmed. Therefore, the occurrence of genetically differentiated subpopulations supports the need to implement independent stock assessments and management measures. none Sabatini, Laura; Bullo, Marianna; Cariani, Alessia; Celić, Igor; Ferrari, Alice; Guarniero, Ilaria; Leoni, Simone; Marčeta, Bojan; Marcone, Alessandro; Polidori, Piero; Raicevich, Saša; Tinti, Fausto; Vrgoč, Nedo; Scarcella, Giuseppe Sabatini, Laura; Bullo, Marianna; Cariani, Alessia; Celić, Igor; Ferrari, Alice; Guarniero, Ilaria; Leoni, Simone; Marčeta, Bojan; Marcone, Alessandro; Polidori, Piero; Raicevich, Saša; Tinti, Fausto; Vrgoč, Nedo; Scarcella, Giuseppe

Common sole (Solea solea) is often the subject of fraudulent species substitutions in processed products because of their excellent organoleptic characteristics and high commercial interest. COIBar-RFLP, a molecular strategy-coupling Cytochrome Oxidase I (COI) DNA barcoding with the consolidated methodology of restriction fragment length polymorphism analysis (RFLP), was applied to search for restriction enzyme polymorphisms useful to discriminate among potential flatfish substitutes of common sole. Seven flatfish species belonging to Soleidae, Bothidae, and Citharidae families were used to construct a reference barcode library of COI sequences. The flatfish species were simultaneously discriminated through specific digestion profiles obtained with the restriction enzyme MspI. We tested the efficacy of COIBar-RFLP on 13 frozen fillets labeled as common sole purchased in local fish markets. These fillets were found to contain three species, S. solea, Solea senegalensis, and Arnoglossus laterna, successfully discriminated by COIBar-RFLP, demonstrating that this method is a rapid and simple sequencing-free molecular approach for these fish species identification in processed seafood products.

Invited feature This work was funded by the European Community's Seventh Framework Programme (FP7/2007-2013) under Grant Agreement No. 266445 for the project Vectors of Change in Oceans and Seas Marine Life, Impact on Economic Sectors (VECTORS). We are grateful to Sophie Pasquier for compiling references.; International audience; Exploited coastal-nursery-dependent fish species are subject to various stressors occurring at specific stages of the life cycle: climate-driven variability in hydrography determines the success of the first eggs/larvae stages; coastal nursery habitat suitability controls juvenile growth and survival; and fisheries target mostly adults. A life cycle approach was used to quantify the relative influence of these stressors on the Eastern English Channel (EEC) population of the common sole (Solea solea), a coastal-nursery-dependent flatfish population which sustains important fisheries. The common sole has a complex life cycle: after eggs hatch, larvae spend several weeks drifting in open water. Survivors go on to metamorphose into benthic fish. Juveniles spend the first two years of their life in coastal and estuarine nurseries. Close to maturation, they migrate to deeper areas, where different subpopulations supplied by different nurseries reproduce and are exploited by fisheries. A spatially structured age-and stage-based hierarchical Bayesian model integrating various aspects of ecological knowledge, data sources and expert knowledge was built to quantitatively describe this complex life cycle. The model included the low connectivity among three subpopulations in the EEC, the influence of hydrographic variability, the availability of suitable juvenile habitat and fisheries. Scenarios were designed to quantify the effects of interacting stressors on population renewal. Results emphasized the importance of coastal nursery habitat availability and quality for the population renewal. Realistic restoration scenarios of the highly degraded Seine estuary produced a two-third increase in catch potential for the adjacent subpopulation. Fisheries, however, remained the main source of population depletion. Setting fishing mortality to the maximum sustainable yield led to substantial increases in biomass (+100%) and catch (+33%) at the EEC scale. The approach also showed how climate-driven variability in hydrography is likely to interact with human pressures, e.g., overfishing increased the sensitivity to unfavourable conditions. Our results provided insights into the dynamics of numerous exploited coastal-nursery-dependent species while paving the way toward more robust advice for sustainable management of these resources.

It is well known that the marine organisms are used as biological indicators for environmental pollution studies. Among these studies, the research on oxidative stress has been increasing in recent years. In this study, mussels (Mytilus galloprovincialis) and fish (Solea solea) samples were collected seasonally from İnciraltı İzmir, Turkey. This station was in an area where fishing is carried out for human consumption. The relationship between 210Po and oxidative stress markers (lipid peroxidation (LPO), H2O2 and proline) was investigated in the mussel tissue (digestive gland, gills) and fish tissue (liver, gills) samples. The present study indicated that H2O2 accumulated with increasing 210Po concentration in mussel samples. Statistically significant correlation were found between H2O2 and 210Po and LPO and proline in mussel samples. This correlation between LPO and proline can be attributed to common environmental parameters (other than 210Po) affecting expression of both LPO and proline levels. There was not a significant correlation between 210Po and LPO levels. Similarly, a significant correlation was not found between 210Po and proline. © 2018 Elsevier Ltd

Tissue-specific accumulation and distribution of polybrominated diphenyl ethers (PBDEs) and their debrominated metabolites were studied in common sole (Solea solea) over an entire reproduction cycle. The fish were dietary-exposed to selected PBDEs in laboratory-controlled conditions for one year. Fish of both sexes were sampled throughout the reproduction cycle and their muscle, liver, viscera, carcass, skin and gonads (female) were analysed for total lipid content, PBDEs and their debrominated metabolites. On a wet weight basis, the concentrations of most spiked congeners showed an increase at the end of the exposure time in the whole body of fish of both sexes. Conversely, BDE-99 and BDE-209 – the two most highly metabolized congeners – did not show a similar increase, while their debrominated metabolites exhibited a linear increase over time. Biomagnification factors (BMFs) calculated in whole body were > 1 for all PBDEs except BDE-99 (0.89 ± 0.22) and BDE-209 (0.013 ± 0.006). BMFs were strongly correlated to apparent assimilation efficiencies, which ranged from 1.6% ± 0.7% (BDE-209) to 88% ± 11% (BDE-100). Fish carcass was the most predominant storage compartment for all PBDEs except BDE-209 in both male and female fish, followed by skin, muscle, female gonads, liver and visceral tissue. BDE-209 showed a different distribution and was stored more predominantly in the liver, viscera and female gonads than other congeners, probably due to its transport with lipoproteins. All PBDEs except BDE-209 showed equilibrium partitioning between the liver and other studied compartments, while BDE-209 showed a higher affinity with blood-enriched tissues, leading to higher liver / carcass, skin and muscle concentration ratios. Visceral tissue and liver exhibited the most pronounced differences in terms of concentration variations between sexes and over time. In females, both tissues showed a significant decrease in most PBDE concentrations (ww) and TLC in March during the spawning season, with low inter-individual variability, reflecting the striking utilisation of lipids by females for reproduction at this time. In males, no differences were found in concentrations in these compartments over time and a high inter-individual variability was observed. Maternal transfer of PBDEs from gonad to eggs was constant, regardless of spawn rank in the spawning season. Egg / gonad PBDE concentration ratios (in lw) were 1.3 ± 0.7 for all congeners and 2.6 ± 0.3 for BDE-209, suggesting a higher transfer of this congener from gonads to eggs.

The present study reports total mercury (THg) and methylmercury (MeHg) concentrations in 32 different lean fish species from the Western Mediterranean Sea, with a special focus on the Balearic Islands. The concentrations of THg ranged between 0.05 mg/kg ww and 3.1 mg/kg ww (mean 0.41 mg/kg ww). A considerable number of the most frequently fish species consumed by the Spanish population exceed the maximum levels proposed by the European legislation when they originate from the Mediterranean Sea, such as dusky grouper (100% of the examined specimens), common dentex (65%), conger (45%), common sole (38%), hake (26%) and angler (15%), among others. The estimated weekly intakes (EWI) in children (7–12 years of age) and adults from the Spanish population (2.7 µg/kg bw and 2.1 µg/kg bw, respectively) for population only consuming Mediterranean fish were below the provisional tolerable weekly intake (PTWI) of THg established by EFSA in 2012, 4 µg/kg bw. However, the equivalent estimations for methylmercury, involving PTWI of 1.3 µg/kg bw, were two times higher in children and above 50% in adults. For hake, sole, angler and dusky grouper, the most frequently consumed fish, the estimated weekly intakes in both children and adults were below the maximum levels accepted. These intakes correspond to maximum potential estimations because fish from non-Mediterranean origin is often consumed by the Spanish population including the one from the Balearic Islands.

Individual-based coupled physical-biological models have become the standard tool for studying ichthyoplankton dynamics and assessing fish recruitment. Here, common sole ( Solea solea L.), a flatfish of high commercial importance in Europe was used to evaluate transport of eggs and larvae and investigate the connectivity between spawning and nursery areas along the western Iberian coast as spatio-temporal variability in dispersal and recruitment patterns can result in very strong or weak year-classes causing large fluctuations in stock size. A three-dimensional particle tracking model coupled to Regional Ocean Modelling System model was used to investigate variability of sole larvae dispersal along the western Iberian coast over a five-year period (2004–2009). A sensitivity analysis evaluating: (1) the importance of diel vertical migrations of larvae and (2) the size of designated recruitment areas was performed. Results suggested that connectivity patterns of sole larvae dispersal and their spatio-temporal variability are influenced by the configuration of the coast with its topographical structures and thus the suitable recruitment area available as well as the wind-driven mesoscale circulation along the Iberian coast.

The present study compares the influence of signals released from fish (common sole, Solea solea L.) and conspecifics on the feeding behavior of the ragworm Alitta virens (Sars) (formerly known as Nereis virens (Sars). Experimental tanks stocked with ragworms were connected to a donor tank by a tube to allow the transfer of water born signal molecules. The donor tanks were stocked with sole and ragworms to create 4 different treatments: “control (blank)”, “ragworms”, “sole” and “sole + ragworms”. All behavioral recordings were made at 19 random days out of a total of 31 feeding days. Video recordings were made each time for 30 minutes starting when first feed entered the tank. All behavioral responses, i.e. latency, numbers and length of ragworms out of burrow were negatively affected when ragworms were exposed to water from “sole + ragworms” donor tanks. When exposed to water from “ragworms” and “sole” donor tanks, the experimental ragworms also reduced their behavioral responses but to a lesser extent than when exposed to the combination of “sole + ragworm” donor tanks. Out-of-burrow activities remained hampered in ragworms exposed to water coming from “sole” and “sole + ragworms” donor tanks at all observation days. Results indicate that signals released by damaged conspecifics and to a lesser extent fish borne cues play an important role in anti-predatory behavior of A. virens.

article i nfo Within coastal nurseries, the distribution of juvenile flatfish may depend on small-scale habitat variability. The presence of ecosystem engineers is known to have important impacts in coastal sediments. Lanice conchilega is a well-known marine ecosystem engineer of shallow soft bottom ecosystems, shaping the macrobenthic community and attracting flatfish. The present study examines the relation between juvenile flatfish and L. conchilega reefs through two experiments. In a field experiment in the Dutch part of the North Sea, the benthic habitat is evaluated by comparing relative differences in numbers of juvenile flatfish between ecosystem engineered habitats and adjacent bare sand (i.e. non-ecosystem engineered) habitats. The hypothetical shelter seeking behaviour was further examined using stomach content analyses. Results show that juvenile plaice Pleuronectes platessa was the dominant species within the tube worm habitat and the species selects specifically for this biogenic habitat. This selection was explained as feeding behaviour. In a complementary laboratory study, food was excluded and the shelter function of the ecosystem engineered habitat was investigated. This experiment quantifies the selection for this habitat by juveniles of the common sole Solea solea. Results from the flume experiment, manipulating the number of tube worms, show that distribution of sole was not random when current velocities are high. The selected habitat is the one with low density tube worm aggregations. Overall, we conclude that structuring benthos plays an important role for juvenile flatfish, both as refuge and as feeding ground. © 2012 Published by Elsevier B.V.

International audience; We explore how alternative hypotheses on the degree of mixing among local subpopulations affect statistical inferences on the dynamics and stock assessment of a harvested flatfish population, namely, the common sole population in the Eastern Channel (ICES area VIId). The current paradigm considers a single, well-mixed, spatially homogeneous population with juveniles from all coastal nursery grounds along the French and UK coasts that contribute to a single adult population and one pool of eggs. Based on the available data and ecological knowledge, we developed a spatial Bayesian integrated life-cycle model that consists of three subpopulations (one near the UK coast and two near the French coast, denoted UK, West FR and East FR, respectively) supported by their respective local nurseries, with the connectivity among the three components limited to low exchanges during larval drift. Considering the population dynamics among three subpopulations (instead of a single homogeneous one) drastically changes our inferences on the productivity of nursery sectors and their relative contribution to total recruitment. Estimates of the East FR subpopulation’s contribution to total recruitment increase (29% in the single population model; 48% in the three subpopulation model), balanced by a decrease in the UK subpopulation’s contribution (53%; 34%). Whereas an assessment based on the hypothesis of a single spatially homogeneous population in the EC indicates exploitation far above MSY (current F/FMSY = 1.8), an assessment that considers a metapopulation with three loosely connected subpopulations revealed a different status, with the UK and East FR subpopulations being exploited above MSY (current F/FMSY = 1.9 and 2, respectively) and the West FR subpopulation approaching full exploitation (current F/FMSY = 1.05). This approach contributes to the quantitative assessment of spatial fishery and coastal habitat management plans.

The gilthead seabream and the soles, Senegalese sole and common sole, are important species in Mediterranean aquaculture. In this chapter, a review of the current genomic resources available for these species is carried out. First, transcriptome information, their main characteristics, and the high-throughput gene expression tools developed in these three species are described. Second, the current genetic maps and their applications for the identification of QTLs for traits of interest in aquaculture are also reported. Moreover, the main features of Senegalese sole genome draft are analyzed and its structure is compared with other Acanthopterygii confirming a high degree of synteny that allows for comparative genomic studies. To show the relevance of these genomic resources to enhance the aquaculture procedures, the SoleaDB database that hosts the genomic information for soles is described. Moreover, main results obtained using transcriptomic tools to decipher the regulatory pathways that control larval development, nutrition and metabolism, as well as the health and welfare status are reviewed. Future directions of genomic research and the impact of novel species-specific applications and resources are highlighted.

Growing demands for marine fish products is leading to increased pressure on already depleted wild populations and a rise in the aquaculture production. Consequently, more captive bred fish are released into the wild through accidental escape or deliberate restocking, stock enhancement and sea ranching programs. The increased mixing of captive bred fish with wild conspecifics may affect the ecological and/or genetic integrity of wild fish populations. From a fisheries management perspective unambiguous identification tools for captive bred fish will be highly valuable to manage risks. Additionally there is great potential to use these tools in wildlife forensics (i.e. tracing back escapees to their origin and determining mislabelling of seafood products). Using SNP data from captive bred and wild populations of Atlantic cod (Gadus morhua L.) and sole (Solea solea L.), we explored the efficiency of population and parentage assignment techniques for the identification and tracing of captive bred fish. Simulated and empirical data were used to correct for stochastic genetic effects. Overall, parentage assignment performed well when a large effective population size characterizes the broodstock and escapees originate from early generations of captive breeding. Consequently, parentage assignments are particularly useful from a fisheries management perspective to monitor the effects of deliberate releases of captive bred fish on wild populations. Population assignment proved to be more efficient after several generations of captive breeding, which makes it a useful method in forensic applications for well-established aquaculture species. We suggest the implementation of a case by case strategy when choosing the best method.

International audience; Simulating fish larval drift helps assess the sensitivity of recruitment variability to early life history. An individual based model (IBM) coupled to a hydrodynamic model was used to simulate common sole larval supply from spawning areas to coastal and estuarine nursery grounds at the meta-population scale (4 assessed stocks), from the southern North Sea to the Bay of Biscay (Western Europe) on a 26-yr time series, from 1982 to 2007. The IBM allowed each particle released to be transported by currents, to grow depending on temperature, to migrate vertically depending on development stage, to die along pelagic stages or to settle on a nursery, representing the life history from spawning to metamorphosis. The model outputs were analysed to explore interannual patterns in the amounts of settled sole larvae at the population scale; they suggested; (i) a low connectivity between populations at the larval stage, (ii) a moderate influence of interannual variation in the spawning biomass, (iii) dramatic consequences of life history on the abundance of settling larvae and (iv) the effects of climate variability on the interannual variability of the larvae settlement success. (C) 2015 Elsevier B.V. All rights reserved.

To protect the welfare of fish at slaughter, these animals should be rendered unconscious and insensible prior to killing. Furthermore, the state of unconsciousnessmust be long enough to allowkillingwithout recovery. The objective of this study was to determine the stunner settings for effective tail-first dry electrical stunning of turbot (Scophthalmusmaximus) and common sole (Solea solea). The fish were separated in two batches (B1 and B2). The turbot and sole in B1were subjected to a short tail-first stun lasting for 1 s and after 1 min of recovery to a second, longer (20 s) stun. The fish in B2were exposed to a single long (20 s) stun, whichwas tail-first in sole, but headfirst in turbot. The short stun was applied to verify that the loss of consciousness was instant (i.e. within 1 s), whereas the long stun (followed by immersion in ice water) was performed with the aim of showing that it is feasible to kill the fish without recovery. Loss of consciousness and sensibility were assessed using electrophysiological (EEG and ECG) and behavioural parameters. After administering a current of 2.39 ± 0.91 A rms by applying 125.5 ± 0.6 V rms (100 Hz) in turbot and 1.22 ± 0.68 A rms by applying 152.4 ± 0.5 V rms in sole for 1 s, 25 out of 26 turbot and 9 out of 10 sole in B1 exhibited EEG patterns showing that the fish were rendered unconscious instantly. The long tail-first exposure of turbot in B1 to 3.88 ± 1.26 A rms for 1 s, followed by 1.44 ± 0.41 A rms for 19 s, followed by immersion in ice water, led to an irrecoverable stun in 21 out of 22 fish, whereas the long head-first stunning of turbot in B2 (n = 13) resulted in passing 1.27 ± 0.40 A rms for 1 s and 0.65 ± 0.21 A rms for 19 s through the fish and no recovery during chilling. After the long, tail-first exposure of sole in B1 (n = 9) and B2 (n = 22) to 1.18± 0.49 A rms for 1 s+0.35 ± 0.22 A rms for 19 s, and 1.20± 0.59 A rms for 1 s + 0.36 ± 0.15 A rms for 19 s, respectively, none of the fish regained consciousness during the chilling. We conclude that the tail-first electrical stunning, followed by immersion in ice water can be developed into an effective stunning and killing method for turbot and sole.

Concern exists about the potential effects of pile-driving sounds on fish, but evidence is limited, especially for fish larvae. A device was developed to expose larvae to accurately reproduced pile-driving sounds. Controlled exposure experiments were carried out to examine the lethal effects in common sole larvae. No significant effects were observed at zero-to-peak pressure levels up to 210 dB re 1 μPa 2 and cumulative sound exposure levels up to 206 dB re 1 μPa 2 ·s, which is well above the US interim criteria for nonauditory tissue damage in fish. Experiments are presently being carried out for European sea bass and herring larvae. © Springer Science+Business Media New York 2016.

For many marine fish species, recruitment is strongly related to larval survival and dispersal to nursery areas. Simulating larval drift should help assessing the sensitivity of recruitment variability to early life history. An individual-based model (IBM) coupled to a hydrodynamic model was used to simulate common sole larval supply from spawning areas to coastal and estuarine nursery grounds at the population scale in the eastern Channel on a 14-yr time series, from 1991 to 2004. The IBM allowed each particle released to be transported by currents from the hydrodynamic model, to grow with temperature, to migrate vertically giving stage development, and possibly to die according to drift duration, representing the life history from spawning to metamorphosis. Despite sensitivity to the larval mortality rate, the model provided realistic simulations of cohort decline and spatio-temporal variability of larval supply. The model outputs were analysed to explore the effects of hydrodynamics and life history on the interannual variability of settled sole larvae in coastal nurseries. Different hypotheses of the spawning spatial distribution were also tested, comparing homogeneous egg distribution to observation and potential larval survival (PLS) maps. The sensitivity analyses demonstrated that larval supply is more sensitive to the life history along larval drift than to the phenology and volume of spawning, providing explanations for the lack of significant stock–recruitment relationship. Nevertheless, larval supply is sensitive to spawning distribution. Results also suggested a very low connectivity between supposed different sub-populations in the eastern Channel.

A description of variations in the chemical composition of fish otoliths at different spatial scales and life history stages is a prerequisite for their use as natural tags in fish population connectivity and migration studies. Otolith geochemistry of juvenile common sole ( Solea solea ), a marine migrant species collected in six Portuguese estuaries was examined. Elemental ratios (Mg:Ca, Mn:Ca, Cu:Ca, Sr:Ca, Ba:Ca, Pb:Ca) were analysed in two zones of the right otolith (corresponding to late larval and juvenile stages) using laser ablation inductively coupled plasma mass spectrometry (ICP-MS). Stable carbon and oxygen isotopes (δ 13 C and δ 18 O) were determined in left otoliths using isotopic ratio monitoring mass spectrometry (irm-MS). Significant differences in otolith geochemical signatures were found among estuaries, among sites within estuaries and between otolith zones. Several elemental ratios (Mg:Ca, Mn:Ca, Cu:Ca and Sr:Ca) showed consistent patterns between otolith zones and were likely influenced by environmental factors and ontogenetic effects associated with physiological changes during metamorphosis. Assignment of individuals to their collection estuary based on the otolith geochemical signatures was more accurate at the site level (81%) than among estuaries (69%). Site temperature was not correlated with any of the elemental or isotope ratios, but salinity was significantly correlated with Ba:Ca, δ 13 C and δ 18 O. Observed spatial variations among estuaries and sites within estuaries indicate that geochemical signatures in otoliths are accurate natural tags of estuarine habitat in common sole. Nevertheless, the significant variations observed between otolith zones should be taken into account in the design of population connectivity studies.

The uptake, elimination and transformation of six PBDE congeners (BDE-28, -47, -99, -100, -153, -209) were studied in juvenile common sole (Solea solea L) exposed to spiked contaminated food over a three-month period, and then depurated over a five-month period. Methoxylated (MeO-) and hydroxylated (OH-) PBDEs were determined in fish plasma exposed to PBDEs and compared to those obtained in control fish. While all MeO- and some OH- congeners identified in fish plasma were found to originate from non-metabolic sources, several OH- congeners, i.e., OH-tetraBDEs and OH-pentaBDEs, were found to originate from fish metabolism. Among these, 4 '-OH-BDE-49 was identified as a BDE-47 metabolite. Congener 4 '-OH-BDE-101, identified here for the first time, may be the result of BDE-99 metabolic transformation. Our results unequivocally showed that PBDEs are metabolised in juvenile sole via the formation of OH- metabolites. However, this was not a major biotransformation route compared to biotransformation through debromination. (C) 2010 Elsevier Ltd. All rights reserved.